2013年度12月大学英语四级仔细阅读习题.docVIP

2013年12月大学英语四级仔细阅读习题（一） Judging from recent surveys,most experts in sleep behavior agree that there is virtually an epidemic (流行病) of sleepiness in the nation. “I cant think of a single study that hasnt found Americans getting less sleep than they ought to,” says Dr. David. Even people who think they are sleeping enough would probably be better off with more rest.　　The beginning of our sleep-deficit (睡眠不足) crisis can betraced to the invention of the light bulb a century ago. From diary entries and other personal accounts from the 18th and 19th centuries, sleep scientists have reached the conclusion that the average person used to sleep about 9.5 hours anight. “The best sleep habits once were forced on us, when we had nothing to do in the evening down on the farm, and it was dark.” By the 1950s and 1960s, that sleep schedule had been reduced dramatically, to between 7.5 and eight hours,and most people had to wake to an alarm clock. “People cheat on their sleep,and they dont even realize theyre doing it,” says Dr. David. They think theyre okay because they can get by on 6.5hours, when they really need 7.5, eight or even more to feel ideally vigorous.　　Perhaps the most merciless robber of sleep,researchers say, is the complexity of the day. Whenever pressures from work,family, friends and community mount, many people consider sleep the least expensive item on his programme. In our society, youre considered dynamic if you say you only need 5.5 hours sleep. If youve got to get 8.5 hours, people think you lack drive and ambition.　　To determine the consequences of sleep deficit,researchers have put subjects through a set of psychological and performance tests requiring them, for instance, to add columns of numbers or recall a passage read to them only minutes earlier. Weve found that if youre in sleep deficit, performance suffers, says Dr. David. “Short-term memory is weakened, as are abilities to make decisions and to concentrate.”　　1. People in the 18th and 19th cent